Spectrum analyzers that detect and log signals that have a constant carrier frequency are well known in the prior art. However, there are an increasing number of sophisticated transmitters that prior art spectrum analyzers will not automatically log in memory. This is particularly true with regard to modern, high tech surveillance devices. To be more specific, AM, FM, and sub-carrier modulated signals are easily logged automatically with a prior art spectrum analyzer, however, a burst transmitter, frequency hopper or spread spectrum transmitter will typically not be logged because there is no stable carrier frequency for the analyzer to lock onto. Furthermore, if a single sweep of the electromagnetic spectrum is performed, there is a good chance that an intermittently transmitting device will not be transmitting during the duration of the sweep. As a result, sophisticated modern surveillance devices use such an intermittent or frequency dispersed transmitter. Therefore, there is a need in the prior art for an improved method and apparatus for detecting the presence of covert surveillance devices that increases the probability that these types of transmitters will be detected.